//招式拆解 II
//https://leetcode.cn/problems/di-yi-ge-zhi-chu-xian-yi-ci-de-zi-fu-lcof/description/
class Solution {
public:
    char dismantlingAction(string arr) 
    {
        char ret = ' ';
        int v[26] = {0};
        for(auto e : arr)
        {
          v[e - 'a']++;
        }
        for(auto e : arr)
        {
          if(v[e - 'a'] == 1)
          {
            ret = e;
            break;
          }
        }
        return ret;
    }
};